Composite construction beam

ABSTRACT

A composite construction beam comprising a first chord and a second chord connected by a web, wherein the first and second chords are made of wood or a wood product and the web is made of a material other than wood or a wood product such as polymer or aluminum. A method of constructing a composite beam includes forming a web from a material other than wood or a wood product and securing it to a first and second chords, which are made of wood or a wood product.

BACKGROUND OF THE INVENTION

Construction beams or girders, elongated beams frequently with anI-shape, are widely used in the construction industry. Theseconstruction components may be used for temporary or permanent supportof horizontal structures. For example, these beams may be used tosupport horizontal concrete slab constructions. These beams mayfurthermore be used as either a primary support, or stringer, or assecondary supports or joists, which run perpendicular to and aresupported by, a stringer.

A wide variety of materials have been used in the past for constructionbeams. Among these are steel, aluminum, and wood. Steel girders orI-beams have long been used in construction. Aluminum beams have alsofound usage. Lumber has also been used for joists and stringers inconstruction for many years. More recently, I-beams have been engineeredfrom engineered wood products such as particle board or fiberboard.Another wood beam that has found use in recent years is an engineeredwood I-beam containing a wood or wood fiber web or vertical element,inserted into a pair of wood horizontal flanges.

These construction beams each have drawbacks to their usage. While steelis certainly durable and resistant to damage from environmentalconditions, its cost and weight make it unsuitable for someapplications. Aluminum is lighter than steel, but it is also subject tomore physical damage due to its greater ductility. Wood and woodproducts are light weight and relatively inexpensive, but are alsosubject to physical damage from abuse and weather conditions. Wood canalso vary in its properties, since it is a natural product.

There is, therefore, a need for an alternative construction beam.

SUMMARY OF THE INVENTION

A composite construction beam comprises wood chords connected by a metalor plastic web.

In one example, the web is aluminum. In another example, the webcomprises four walls enclosing a cavity. In another example, the fourwalls of the web extend beyond the cavity enclosed by the four walls.Stated another way, the walls of the web extend perpendicularly from thearea enclosed by the walls on all four sides. The web has a height, awidth and a length. The dimensions of the web, and therefore the lengthof the beam itself, may vary according to the demands of a particularapplication. The walls that extend upward and downward from the web mayprotrude into the chord or flange. The chord may be wood or a woodproduct, which extends along the length of the web. It is alsoenvisioned that the web may be made of a polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is cross sectional view of an example of a composite constructionbeam; and

FIG. 2 is a side perspective view of an example of a compositeconstruction beam.

DETAILED DESCRIPTION OF THE INVENTION

The following examples should not be viewed as limiting the scope of theinvention. The claims will serve to define the inventions. In thefollowing description, the composite construction beam will be describedrelative to a standard orientation of an “I-beam” in use, with a firstflange or chord referred to as a “top” chord and a second flange orchord referred to as a “bottom” chord.

A composite construction beam comprises a pair of wood chords orflanges, connected by a metal or plastic web. In one example, shown inFIGS. 1 and 2, a composite construction beam 10 comprises top chord 20and bottom chord 22 connected by a web 15. Web 15 comprises four wallsenclosing a cavity 11, namely first 12 and second 14 side walls, a topwall 16 and a bottom wall 18. The first and second side walls 12, 14 mayextend beyond cavity 11 so that they extend into top 20 and bottom 22chords, located above and below the web respectively. First and secondside walls 12, 14 may extend at least about 30, 40, 50, 60, 70, or 80percent or more into top and bottom chords 20, 22. In one particularexample, first and second side walls extend about 50 percent into topand bottom chords 20, 22. Side walls 12, 14 may be secured in place byglue (not shown), or by pins 28 inserted through the chords and sidewalls 12, 14, or similar methods or combinations thereof. In oneparticular example, pins 28 are spaced apart about 19 inches (48 cm) oncenter. Other spacings may also be used, such as any spacing between 12inches (30.5 cm) and 24 inches (61 cm).

Top wall 16 may extend beyond the side walls 12,14 and adjoin the topchord 20 along a majority of the bottom surface 24 of top chord 20 andthe bottom wall 18 may extend beyond the side walls 12,14 and adjoin thetop surface 26 of the bottom chord 22. Top and bottom walls 16, 18 mayextend along at least about 60, 65, 70, 75, 80, 85, 90, 95, or evenabout 100 percent of the adjoining surface of top and bottom chords 20,22, respectively. In one particular example, top and bottom walls 16, 18may extend along about 91 percent of the adjoining surface of top andbottom chords 20, 22, respectively.

The thickness of first and second side walls, top wall and bottom wall12, 14, 16, 18 may also vary according to the requirements of aparticular application. In some examples, first and second side walls,top wall and bottom wall 12, 14, 16, 18 are between about 0.05 inches(1.3 mm) and about 0.5 inches (1.3 cm) thick. In one particular example,one or more of walls 12, 14, 16, 18, are about 0.094 inches (2.4 mm)thick ±0.015 inches (0.4 mm). In some examples, the widths of walls 12,14, 16, 18, are at least approximately identical. In other examples, itis envisioned that the widths of side walls 12, 14 may differ from thewidths of top wall 16 and bottom wall 18.

In one particular example, when web 15 is viewed in cross section, sidewalls 12, 14 define an overall height of about 6 inches (15.2 cm) andtop and bottom walls 16, 18 define an overall width of about 2.9 inches(7.4 cm). Side walls 12, 14 and top and bottom walls 16, 18 enclose acavity about 1 inch (2.5 cm) wide and about 4.7 inches (11.9 cm) high.Top and bottom walls 16, 18 extend about 0.84 inches (2.1 cm) past sidewalls 12, 14. Similarly, side walls 12, 14 extend about 0.65 inches (1.6cm) past top and bottom walls 16, 18. Each of walls 12, 14, 16, 18 isabout 0.1 inches (0.25 cm) thick. Chords 20, 22, in cross section, areabout 1.5 inches (3.8 cm) in height and about 3.15 inches (8.0 cm) inwidth. Side walls 12, 14 are inserted into chords 20, 22 and top andbottom chords 20, 22 adjoin top and bottom walls 16, 18, respectively.Web 15 maybe secured in top and bottom chords 20, 22 with the use ofglue (not shown), pins 28 inserted into chords 20, 22 and through sidewalls 12 and 14, or both glue and pins 28. Other methods of securing web15 to chords 20, 22 may also be used.

In another example, when web 15 is viewed in cross section, side walls12, 14 define an overall height of about 6.52 inches (16.6 cm) and topand bottom walls 16, 18 define an overall width of about 2.86 inches(7.3 cm). Side walls 12, 14 and top and bottom walls 16, 18 enclose acavity about 0.98 inch (2.5 cm) wide and about 4.65 inches (11.8 cm)high. Top and bottom walls 16, 18 extend about 0.84 inches (2.1 cm) awayfrom side walls 12, 14. Likewise, side walls 12, 14 extend about 0.84inches (2.1 cm) past top and bottom walls (16, 18). Each of walls 12,14, 16, 18 is about 0.1 inches (0.25 cm) thick. Chords 20, 22, in crosssection, are about 1.675 inches (4.3 cm) in height and about 3.15 inches(8.0 cm) in width.

Gussets or reinforcing beads 19 maybe present at one, two, three or allfour inside joints, that is, the joints facing cavity 11, where sidewalls 12, 14 meet top and bottom walls 16, 18. Alternatively or inaddition, reinforcing beads or gussets 19 may be present on one or moreof the outside joints where side walls 12, 14 meet top and bottom walls16, 18. In one particular example, the reinforcing beads or gussets forman arc having a radius of about 0.19 inches (0.5 cm). Reinforcing beadsor gussets with other radii may also be used, such as, for example, 0.03inches (0.8 mm), 0.05 inches (1.3 mm), 0.3 inches (0.8 cm) or 0.5 inches(1.3 cm). Other dimensions of the reinforcement may also be used. Aswith the previous example, side walls 12, 14 are inserted into chords20, 22 and top and bottom chords 20, 22 adjoin top and bottom walls 16,18, respectively.

In still another example, web 15 comprises side walls 12, 14 defining anoverall web height of about 6.03 inches (15.3 cm) and an overall widthof 2.875 inches (7.3 cm) inserted into the longest sides of a pair ofchords having dimensions of 3.15 inches (8.0 cm) by 1.675 inches (4.3cm). Side walls 12, 14 and top and bottom walls 16, 18 enclose a cavityabout 1.0 inch (2.5 cm) wide and about 4.5 inches (11.4 cm) high. Topand bottom walls 16, 18 extend about 0.84 inches (2.1 cm) away from sidewalls 12, 14. Side walls 12, 14 extend about 0.66 inches (1.7 cm) pasttop and bottom walls (16, 18). Each of walls 12, 14, 16, 18 is about 0.1inches (2.5 mm) thick. Chords 20,22, are about 1.675 inches (4.3 cm) inheight and about 3.15 inches (8.0 cm) in width. Reinforcing beads 19 arepresent at all four inside joints where side walls 12, 14 meet top andbottom walls 16, 18, providing a radius of 0.05 inches (1.3 mm).Additionally, reinforcing beads 19 are also present on all 12 of theremaining outer joints where side walls 12, 14 meet top and bottom walls16, 18. Each of the reinforcing beads on the outer joints of web 15provides a radius of approximately 0.03 inches (0.8 mm).

A set of several composite construction beams was made with an aluminumweb having an overall height of 6.03 inches (15.3 cm) and an overallwidth of 2.875 inches (7.3 cm) inserted into a pair of chords 3.15inches (8.0 cm) by 1.675 inches (4.3 cm) in dimension, as describedabove. The beams were tested for deflection under defined loads byplacing the beam between supports placed 7 feet, 10.5 inches (240 cm)apart with the load applied to a 28 inch (71 cm) section in the centerof the beam. A control beam of a commercially available engineered woodgirder (Klenk Holz AG, Oberrot, Germany) of similar dimensions was alsotested. The amount of deflection for the load applied in the test isprovided in Table I.

TABLE I Deflection for Load Applied 1000 lbs 2000 lbs 3000 lbs 4000 lbs5000 lbs 6000 lbs 7000 lbs 8000 lbs 10000 lbs Sample (454 kg) (907 kg)(1361 kg) (1814 kg) (2268 kg) (2722 kg) (3175 kg) (3629 kg) (4536 kg) 11.6 mm 4.8 mm 6.4 mm  8.0 mm  9.5 mm 11.1 mm 12.7 mm 14.3 mm 19.1 mm 21.6 mm 4.8 mm 8.0 mm 11.1 mm 14.3 mm 17.5 mm 20.7 mm 25.4 mm 33.4 mm 33.2 mm 8.0 mm 11.1 mm  14.3 mm 17.5 mm 22.2 mm 25.4 mm 28.6 mm 38.1 mm 43.2 mm 6.4 mm 9.5 mm 12.7 mm 15.9 mm 19.1 mm 22.2 mm 27.0 mm 36.5 mmControl 3.2 mm  8.0 mm 11.1 mm 15.9 mm 22.2 mm

Sample 1 was assembled with glue and pins securing the web in thechords. Samples 2-4 utilized only pins to do the same. In samples 1-4,the pins were spaced from each other 19 inches (48.3 cm) on center.While not wishing to condition patentability on any particular theory,the variations between samples in deflection are believed to be dueprimarily to variations in the wood chords used. As a natural product,the wood used in the chords can vary in strength and other propertiesaccording to species and grade as well as simply varying from piece topiece. This indicates that the composite construction beam is animprovement on prior construction beams, since the compositeconstruction beam eliminates one source of natural variation in woodquality by utilizing an aluminum web.

The maximum load bearable by a composite girder was also determined. Theaverage maximum load for the above samples was 11862.5 lbs (5381 kg),which compares favorably to the capacity of an all lumber constructionbeam. Furthermore, the composite girder shows improved performance inother parameters. The composite girders show about 50 percent greatershear strength than wood girders and greater than 100 percent greatertension strength as determined as follows.

The shear strength of a 12 inch section of a composite girder was testedby placing the girder section on a solid, unyielding base surface andapplying a load to the top surface of the girder until the girderfailed, i.e. until the web portion of the composite girder buckled. Theload was applied to a 4 inch (10.2 cm) square plate placed on top of thegirder and the load was applied through a round bar to distribute theload equally across the girder. The ultimate load that caused failure ofthe web was 14,900 pounds (6759 kg). This represents an approximately 50percent increase in shear strength over prior all wood girders ofsimilar design.

The tension strength of the composite girder was tested in two differentways. In the first tension test, a series of three 18 inch (45.7 cm)sections of composite girder were assembled by stacking the sections,with the second (middle) composite girder section in the series orientedapproximately perpendicular to both the first composite girder sectionand the third composite girder section (i.e., the first and third girdersections were approximately parallel). The bottom composite girdersection was secured in the testing machine by clamping the entire lengthof the bottom chord and bottom wall (18 in FIG. 1) of the aluminum webin the testing machine. The top composite girder section was similarlysecured in the testing machine, by clamping the entire length of the topchord and the top wall (16 in FIG. 1) of the aluminum web in the testingmachine. The middle composite girder section was clamped atapproximately right angles to each of the top and bottom compositegirder sections by a pair of clamps. One pair of clamps encompassed thetop chord and top wall of the web of the bottom girder section and thebottom chord and bottom wall of the web of the middle girder section;each clamp flanking the girders on opposite sides. Similarly, the secondpair of clamps attached the middle girder section to the top girdersection, encompassing the top chord and top wall of the web of themiddle girder section and the bottom chord and bottom wall of the web ofthe top girder section, with the two clamps within the pair beinglocated on opposite sides of the girder sections. The test involvedapplying force to attempt to pull the assembled girder sections apart.In this test, an ultimate tension of 2,950 pounds (1338 kg) was appliedwhen the clamps failed, rather than any of the girder sections.

A second tension test was then performed as described above, but withtwo composite girder sections (18 inches (45.7 cm) long) arranged one ontop of another, approximately perpendicular to each other. As with theprevious tension test, the bottom composite girder section was securedin the testing machine by clamping the entire length of the bottom chordand bottom wall of the aluminum web in the testing machine and the topcomposite girder section was secured in the testing machine by clampingthe entire length of the top chord and the top wall of the aluminum webin the testing machine. The top and bottom girder sections were thenclamped together with a series of four clamps. Again the testing machineattempted to pull the top and bottom beam apart and again, the clampsfailed prior to the composite beam failing. In this particular test, theultimate tension was 4,950 pounds (2245 kg) when the clamps failed. Thisrepresents greater than 100 percent improvement over prior wood girders.

A composite beam of the type described herein may be constructed byforming a web of a material other than wood or wood products andsecuring the web to a first and a second chord made of wood orwood-product. In one example the web is aluminum and may be formed as asingle piece by extrusion or other similar methods. It is alsoenvisioned that a polymer web may also be used. The web may be securedto the first and second chords with glue, pins or a combination thereof.The web may comprise first and second side walls that project into andare attached to the first and second chords. The web may also include analuminum top wall and an aluminum bottom wall. The top wall and thebottom wall may intersect the first and second side walls, enclosing acavity. The web may also include one or more reinforcing beads orgussets located at the intersection of the side walls with the top andbottom walls.

A composite beam as described herein may be used in a method ofconstruction to support a structure. As provided above, the compositebeam used in such a method comprises a first chord and a second chordconnected by a web. The first chord and second chord are made of wood orwood products and the web is made of a material other than wood or woodproducts such as polymer or metal as described above.

Based upon the foregoing disclosure, it should now be apparent that thecomposite construction beam will carry out the objects set forthhereinabove. It is, therefore, to be understood that any variationsevident fall within the scope of the claimed invention and thus, theselection of specific component elements can be determined withoutdeparting from the spirit of the invention herein disclosed anddescribed.

1. A composite construction beam comprising a first chord and a secondchord connected by a web, wherein the first and second chords are madeof wood or a wood product and the web is made of a material other thanwood or a wood product.
 2. The composite construction beam of claim 1,wherein the web comprises at least one aluminum wall that projects intoand is attached to the first and second chords.
 3. The compositeconstruction beam of claim 1, wherein the web comprises first and secondaluminum side walls that project into and are attached to the first andsecond chords.
 4. The composite construction beam of claim 3, whereinthe web additionally comprises an aluminum top wall and an aluminumbottom wall, wherein the top wall and bottom wall intersect the firstand second side walls, enclosing a cavity.
 5. The composite constructionbeam of claim 4, wherein the top and bottom walls project from the firstand second side walls and adjoin the first and second chords.
 6. Thecomposite construction beam of claim 3, wherein the web additionallycomprises one or more gussets or reinforcing beads located at theintersection of the side walls with the top wall, the bottom wall orboth.
 7. The composite construction beam of claim 4, wherein the web isa unitary, extruded structure.
 8. A method of construction comprisingutilizing a composite construction beam to support a structure, whereinthe composite construction beam comprises a first chord and a secondchord connected by a web, wherein the first and second chords are madeof wood or a wood product and the web is made of a material other thanwood or a wood product.
 9. The method of claim 8, wherein the webcomprises at least one aluminum wall that projects into and is attachedto the first and second chords.
 10. The method of claim 8, wherein theweb comprises first and second aluminum side walls that project into andare attached to the first and second chords.
 11. The method of claim 10,wherein the web additionally comprises an aluminum top wall and analuminum bottom wall, wherein the top wall and bottom wall intersect thefirst and second side walls, enclosing a cavity.
 12. The method of claim11, wherein the top and bottom walls project from the first and secondside walls and adjoin the first and second chords.
 13. The method ofclaim 11, wherein the web additionally comprises one or more gussets orreinforcing beads located at the intersection of the side walls with thetop wall, the bottom wall or both.
 14. The method of claim 11, whereinthe web is a unitary, extruded structure.
 15. A method of making acomposite construction beam, the method comprising: forming a web of amaterial other than wood or wood products; and securing the web to afirst chord and a second chord made of wood or a wood product.
 16. Themethod of claim 15, wherein the web is aluminum.
 17. The method of claim15, wherein the web is formed by extrusion.
 18. The method of claim 16wherein the web is secured to the first and the second wood chords bypins, glue or a combination thereof.
 19. The method of claim 18, whereinthe web comprises first and second aluminum side walls that project intoand are attached to the first and second chords.
 20. The method of claim19, wherein the web additionally comprises an aluminum top wall and analuminum bottom wall, wherein the top wall and bottom wall intersect thefirst and second side walls, enclosing a cavity.
 21. The method of claim20, wherein the web additionally comprises one or more gussets orreinforcing beads located at the intersection of the side walls with thetop wall, the bottom wall or both.